2025 Gmc At4 2025 Diesel Engine. With its base engine, the 2025 sierra is rated at up to about 19 mpg in the city and 22 mpg on the highway. View detailed specs, features and options for the 2025 gmc sierra 1500 4wd crew cab 147 at4 at u.s.

Initially introduced on select trims, the lzo duramax diesel is now the base engine for the at4x. Of torque on premium fuel.